You absolutely cannot eat that chicken until it is cooked to a minimum temperature of 161 F.
Marinating in lemon or anything else does not remove the danger of eating raw chicken.
If you're thinking of ceviche where the acidic marinade "cooks" the food, forget it. The acidic marinade denatures the protein so it looks like it's been cooked but is has not. However, since heat has not been applied, bacteria present will not be killed and can make you very ill.
A lemon marinade for chicken will do the trick in a couple of hours.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan